There are some well-know limits with this example: - Even with NDO_AUTO_14443_4A enabled (default), nfc-poll can miss ATS. That due to the way the PN532 use to poll for ISO14443 type A, it will attempt to find ISO14443-4-only targets, then ISO14443-3. If your ISO14443-4 target is present when PN532 looks for ISO14443-4-only, ATS will be retrieved. But if your target enter the field during ISO14443-3, RATS will not be sent and ATS not retrieved. - nfc-poll can show up only one card while two are in field. That's due, again, to the way the PN532 poll for targets. It will stop polling when one modulation got a result, so if you have, for example, one ISO14443-3 (eg. Mifare Ultralight) and one ISO14443-4 (eg. Mifare DESFire), it will probably return only the ISO14443-4.